Ball mill with tensional and wear-resistant linings



N. L.HALL.

Aug. 30, 1966 BALL MILL wmf TENsIoNAL AND wam-RESISTANT mames 5Sheets-Sheet 1 Filed Nov. 27, 1963 Aug. 30, 1966 N. L. HALL.

VBALL MILL WITH TENSIONAL AND WEAR-RESISTANT L'ININGS Filed Nov. gv.19s?.Y

3 Sheets-Sheet 2 INVENTOR. www

N. L. HALL Aug. 3o, 1961s 3,269,668 BALL MILL WITH TENSIONAL ANDWEAR-RESSTAN' LININGS med Nov. 2v, 196s 3 Sheets-Sheet 3 Fig. 10,

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United States Patent Olce 3,269,668 Patented August 30, 1966 3,269,668BALL MILL WITH TENSIONAL AND WEAR- RESISTANT LININGS Newton L. Hall,P.0. Box 83, Zone 10, vSalt Lake City, .Utah Filed Nov. 27, 1963, Ser.No. 326,486 2 Claims. (Cl. 24l-137) This invention refers to the liningand associated parts.

which are applicable to cylindrical crushing or grinding mills used forthe comminution or size reduction of rock, ores, or similar elements bybreaking or grinding operations as employed for ore reduction.

The particular application as described in this sepcica- .The extendedapplication of this type of mill may be used for the crushing, grindingor processing and finishing of ore or cement, other uses being for themixing, classification, processing and finishing of chemicals, and theagglomerating or' pelletizing of granular substances for the extensionof a processing treatment. The horizontal rotary mill has a wideapplication in the industries due to its practical shape, low upkeep,efiiciency of operation, and high capacity.

Ball mills are so termed in the trade when using balls as a grindingmedia in the mill load; rod mills when using rods or bars, and tubemills when using balls, or balls and rods in mills of several diametersin length of cylinder.

No definite dividing line exists in size reduction between the termscrushing and grinding. One is a term of violent compression, and theother is a compression extended to y* a microscopic state-the breakingof one part into two,

crushing into grinding. The division conforms to the trade parlance, anidiom of common speech.

Ball mills are in common use for fine grinding and may be of thehorizontal rotary cylinder of uniform diameter or of the conical milltype and produce a product of over 200 mesh per square inch in screensize. Large size of balls of over four inch in diameter are usedprimarilyfor crushing in mills approximating ten feet in diameter, andballs of less than two inches in diameter are used for fine grinding.

The -collective weight of steel balls will average 300A pounds per cubicfoot and combined with mill pulp, will increase the weight to 400 poundsper cubic foot. Grinding mills will average from 7 to 14 feet or more indiameter with ball mills of two diameters in length and tubev mills ofgyratory or jaw type of Crusher and then pass the broken ore over ascreen termed a grizzly or grate, and in turn delivering the undersizeto a primary roll or disc capacity. The long rods are in axial alinementwithin the mill and turn diametrally of the rod in radial movement` of 5to 15 feet, holding a mill feed of coarse or mine-run of rock to becrushed in a substantially vertical and free fall with the crushed orepassing over the mill load in an impact action upon the ore and rock atthe load toe below.

Horizontal rotary grinding mills have mill cylinders which arenecessarily involved with an enclosed load grinding element; of itself,lthe rotating mill is a hollow cylinder which does not perform aneffective service with` out the tumbling and rotating action of acontained grinding element, the combination of the mill cylinder as aunit with a grinding element as balls, rods, or diametral walls asanother and contained unit to perform an eil'ective grinding result. Therotating mill cylinder combined with the active grinding elementscomprise the mill and apparatus. Useless each without the other.

. Various grinding applications can be made for use of the ball type ofmill. In the following application. the references used are for orereduction.

Types of grinding mill are on the market wherein the mill casings andcasing heads are lined with plates of alloyed steel to withstand thevigorous and rugged wear of the rotating mill load which is composed ofhard steel lballs forming the grinding element of the mill load, theballs being made necessarily hard to fracture a hard or harder oreintermixed within the mill load. The mill action is severe, andnecessarily so to create the impact ory grind required to pulverize theore sufficiently for the liberation of the frequently microscopicmineral content in the ore. The milling action is an impact crushingforce, and in the ball type of mill, the constant impelling action ofthe mill load with its contained load of balls or rods is an incessantbattering of the mill load in rotating and cascading at rotationsvarying from l0 to 50 -rotations per minute, the rotations varying withthe size of mill diameter. To withstand such a wearing action theinterior lining of the 4mill casing and of other interior surfaces mustbe of an abrasion-resistant material equal to the abrading4 severity ofthe mill load. The mill and lining equipment must serve over an extendedperiod of time to warrant the expense of milling operations of which thecost of reducing mine-run size of ore to concentrate size forms thechief item of expense. The ball mill is a sec-v ondary mill in thegrinding circuit, such as; the mine-run of rock and ore must be reducedto screen size by the Crushers, jaw or gyratory so that the ball millfeed can act on the crushed ore and effect its pulverization to apowdered form, reduced in size of the mineral particle, ordinarily to ascreen size of over 200 or finer mesh per square inch. Ball mills rangein size from 7 to 16 feet in diameter and in mill lengths to 20 feet,the mill diameter and length of cylinder bear a relation to effect thedesired size of mill product. The severity of the impact and cmshingactions within a rotating ball mill demands mill linings of alloyedsteel composition to warrant the highv Crusher, and then to a primaryball mill, delivering the product to secondary ball mills using smallballs for extreme fine grinding. Rod mills are of the same constructionas ball mills and use steel rods or bars of substantially the length ofthe cylindrical mill interior. Steel rods are of diameters up to 4inches and a mill load of rods may fill the mill almost to one-half ofthe volumetric mill heavy castings to remote locations where they areused. Constant improvements are being made in the quality of such steelswith regard to their length of service in the field.

Liner castings are made to a man size for ease of installation and suchcastings are attached to the mill shell by bolting with the bolt holesbeing made through the mill shell with the inner face of the cast linerplate being formed to an undulating shape to provide a grip tothe millloadv for its rotation. The texture of the load inrotation eliminatesthe necessity for a load lifter.'

A mill with a compartment wall feature has the load lifted by thecompartment wall.

The protection provided by a shell lining to the mill cylindrical vcasing is of utmost importance, for if the lining starts to fail andthen permits the rotating load to attack the mill casing, a casing whichis of soft steel and lacks the resisting qualities of a lining ofalloyed steel, then a ruination of the shell can become apparent withina short time measured by a very few hours, vmaking a replacement in downtime of plant operation serious. The cost of reducing the mine-run ofrock to an almost impalpable powder forms the chief expense of operationin ore benefication.

The weight of rotating mill loads are measured in tons and the liningand wall structure must have a tensile strength to withstand theconstant variation of weights and impacts which the falling loadsdevelop. Hard iron castings are subject to fracture and liner castingsof the mill shell require bolting attention, likewise the necessity forperforating the mill shell to hold the heavy liner castings forms anexpense which can be eliminated, as shown in the herein specification.

Mill linings are of uniform thickness and of few parts per mill beingsuccessively installed through an opened trunnion or through a cylinderhead opened by removal of either mill head. For an original millconstruction, the mill lining or lining and compartment wall, may beinstalled within the mill cylinder at the place of manufacture intact,the ball mill being formed virtually complete and ready for installationon the foundations at the following place for use or operation.

In the following descriptions reference may be made to United StatesLetters Patent having been issued to the applicant herein: Patents Nos.1,315,770, 2,580,541, and 2,653,769.

Objectives One of the objectives of this invention is, to incorporatewithin a grinding mill with shell lining or compartment wall members, acombination of structural elements possessing .inherent and residualtensile strength subject to milling stress and strain resistance, plusabrasion-resistant members of a composite character lling the openshapes ush with the web of the structural shape.

Another objective is to develop a milling action within a rotating millcylinder which can accommodate a milling load of approximately 50percent of the volumetric capacity of the mill cylinder, accept andcrush a primary ballmill feed and produce a ground product whichapproximates a secondary mill feed, this objective being to effect theelimination of the primary mill and combining the primary and secondarymill within this objective.

Another objective is to concentrate the primary and secondary cost ofequipment and operation such as time of circuit, economy of power,economy of mill oor space, elimination of down-time for replacements,and, production of an angular rather than a rounded or spherical shapeof an individual particle of the finely ground product.

Another objective is to produce a crushing action on the mill load whichwill develop a greater percentage of angular crushed fines of a coarserscreen size and offer a greater elimination of nes which effect slimesin the mill product.

A further objective is to provide a crushing action which conformsclosely to a characteristic natural impact action of piece sizereductioncrushing to grinding. f A further objective is to maintain acascade or overfall of mill load surface action which is based upon thelaws of gravity fall; this in point of crushing action upon the millload.

Reference is made to the following drawings which form a part of thesespecifications and wherein similar reference characters refer to similarparts in all of the views:

' taken on line 3-3 of FIG. 1.

FIGURE l is a longitudinal and vertical section of a grinding mill withcompartment wall taken on line 1-1 of FIG. 2 showing the compartmentwall in position and wherein the mill shell or casing is noted by thenumeral l with open cylinder heads 2a for the feed head and 2b for thedischarge head.' The open head trunnion is noted as 3a at the feed headand 3b at the discharge head with the mill rotating on the bearings 3cat the feed head and 3d at the discharge head. The feed scoop 3e isattached to and rotated with the feed trunnion. At the feed end of themill casing the driving gear 4 is attached driven by the driving pinion5 from the drive shaft 6 (FIG. 2) which is operated by any suitablemotive power.

FIGURE 2 is a cross section of the mill casing l holding a mill lining 7formed of mill structural channels supporting a compartment wall`section 8 with open balancing space or slot 9, the spacing beingprovided by a channel segment 9a of FIG. 1. As events require thecrescent lining mem-ber of FIG. 2 shown as 'structural steel channelsmay be substituted by crescent members of hard iron or cast steel. Thecompartment wall shown in section 8 of FIG. 2 is formed of structuralsteel as shown in FIGS. 6, 7, 8 and 9, with channel terminals as shownin FIG. 5.

FIGURE 3 is a longitudinal and vertical section of a grinding mill withcompartment wall the section being The terminal sections of thecompartment wall 8a are notched to a half section width to provide freespace for widths of the two largest balls in use to avoid casting withprotective coveringof the section. The balancing slot 9 of thecompartment wall 8 is of a width greater than a 2 ball space, the slotbeing retained in width of spacing by the segment channel 9a beinginterrnediateto adjoining channel lining members 7.

FIGURE 4 is an enlarged cross section of a portion of the mill shell orcasing with sections of the structural lining members as 7A, 7-B, and7-C being shown in position to protect the mill casing under protectionfrom action by vagrant mill loads. Section 7-B shows an advancingfailure of the abrasion-resistant filling of the channel lining at 71with the failure approaching the mill shell casing 1 at 7g. Theprotection afforded by the covering of the web plate of the channellining provides an advance warning to the mill operator for -removal ofthe mill from service prior to an injury to the mill casing 'at 7grequiring a shut down from service of the mill rather than a replacementof the defective lining section 7-B. The mill channel sections as 7-Aare filled with an abrasion-resistant element as 7e being reinforced inposition between the channel flanges of each channel section as shown insections 7A and 7-C. The abrasion-resistant filling element 7e may be ofa suitable material which is non-shattering and of wearing qualities.

FIGURE 5 shows enlarged terminal portions of the compartment wall 8 inposition between two opposite terminal portions of adjacent crescentliner sections, the terminal 7h being shown in section with the bearing=por tion against the terminal of the compartment wall being reinforcedwith a formed plate 7m welded to the channel section. The oppositechannel liner 7j and basing plate is shown in elevation.

FIGURE 6 is an end view of an I beam shown in FIG. 7 showing the linesof flange torch cuts, A-A and B-B' being cut to the depths as noted indash lines to be bent to the upper terminal and formed to the positionC-C' andD-D'. The extended web portion E and F are cut to size as shownand replaced on the under side of the bent flanges and welded to jointhe extended flanges at CD' and form a support to the extended web L atC'D'. A similar modification is made at the lopposite terminal of the Ibeam wall section shown at FIG. 7.

FIGURE 7 is an abbreviated length of a wall section R shown inelevation, with the web plate shown extended as a unit of the I beamwall section, at L.

FIGURE 8 is a longitudinal section taken on line 8- 8 of FIG. 7, showingin abbreviated length a compartment wall section with plates E and F inunder position -to the bent flanges at E' and F' and welded to position.lThe abrasion-resistant filling is shown in position covering andprotecting the web of the I beam member.

FIGURE 9 is an under view of a completed wall sectionas shown in FIG. 7with the anges being shown in position along lines B-B' and A-A andwelded to the beam web at L.

FIGURES 10, 1l and 12 are diagrammatical views of liner rings in sideelevation with FIG. 10 being of a circular lining, FIG. 1l of twocrescent liners with compartment wall intervening, and FIG. 12 being ofa circular lining and notched to accept the compartment wall and lugs.

I claim:

1. In a grinding mill, the combination with a rotary drum comprising; acylindrical drum with an imperforate casing with open trunnion bearingshaving open casing Iheads positioned at each end of said drum, saidcasing provided with an interior structural steel channel lining .ofhigh tensile strength with abrasion-resistant elements placed in thevopen spaces between flanges of said lining channels, said interiorlining having a plurality of circular lining members forming a compositering or crescent lining curved to an inner circular radius of saidcasing, with the outer web surface of said channels facing andprotecting the adjacent portion of said mill casing from vagrant loadsand penetrating mill wear, said composite lining members supporting acomposite diametral Wall formed of lstructural beams of high tensilestrength with the open spaces between flanges being. filled withabrasion-resistant filling elements for wear protection, said wall andlining being mutual in support and independent of attachment to saidcasing, said wall being positioned in mill diametral and axial alignmentanddividing said drum interior into two semicylindrical compartments ex-`tending along each side of said wall, said composite wall having aplurality of similar wall lengths with open spaces intervening thecomposite lengths, said spaces providing free access by gravity betweensaid parallel compartments 'i i for ingress or egress of portions ofsaid load during successive rotations of said grinding mill.

' 2. A combination as set forth in claim 1 wherein the mill casing is ofuniform diameter and imperforate, with the interior casing liningcomprising standard channel sec.l

References Cited by the Examiner UNITED STATES PATENTS 1,872,036 i 8/1932 Hardinge 241--182 X 2,580,541 1/ 1952 Hall 241--176 X; 2,653,769 9/1953 Hall 241-137 3,194,506 8/1965 Bourne A--- 241-182 X ROBERT C.RIORDON, Primary Examiner.

PEPPER, IR., Assistant Examiner.

1. IN A GRINDING MILL, THE COMBINATION WITH A ROTARY DRUM COMPRISING; ACYLINDRICAL DRUM WITH AN IMPERFORATE CASING WITH OPEN TRUNNION BEARINGSHAVING OPEN CASING HEADS POSITIONED AT EACH END OF SAID DRUM, SAIDCASING PROVIDED WITH AN INTERIOR STRUCTURAL STEEL CHANNEL LINING OF HIGHTENSILE STRENGTH WITH ABRASION-RESISTANT ELEMENTS PLACED IN THE OPENSPACES BETWEEN FLANGES OF SAID LINING CHANNELS, SAID INTERIOR LININGHAVING A PLURALITY OF CIRCULAR LINING MEMBERS FORMING A COMPOSITE RINGOR CRESCENT LINING CURVED TO AN INNER CIRCULAR RADIUS OF SAID CASING,WITH THE OUTER WEB SURFACE OF SAID CHANNELS FACING AND PROTECTING THEADJACENT PORTION OF SAID MILL CASING FROM VAGRANT LOADS AND PENETRATINGMILL WEAR, SAID COMPOSITE LINING MEMBERS SUPPORTING A COMPOSITEDIAMETRAL WALL FORMED OF STRUCTURAL BEAMS OF HIGH TENSILE STRENGTH WITHTHE OPEN SPACES BETWEEN FLANGES BEING FILLED WITH ABRASION-RESISTANTFILLING ELEMENTS FOR WEAR PROTECTION, SAID WALL AND LINING BEING MUTUALIN SUPPORT AND INDEPENDENT OF ATTACHMENT TO SAID CASING, SAID WALL BEINGPOSITIONED IN MILL DIAMETRAL AND AXIAL ALIGNMENT AND DIVIDING SAID DRUMINTERIOR INTO TWO SEMICYLINDRICAL COMPARTMENTS EXTENDING ALONG EACH SIDEOF SAID WALL, SAID COMPOSITE WALL HAVING A PLUALITY OF SIMILAR WALLLENGTHS WITH OPEN SPACES INTERVENING THE COMPOSITE LENGTHS, SAID SPACESPROVIDING FREE ACCESS BY GRAVITY BETWEEN SAID PARALLEL COMPARTMENTS FORINGRESS OR EGRES OF PORTIONS SAID LOAD DURING SUC-NTS CESSIVE ROTATIONSOF SAID GRINDING MILL.